OFFSET
0,3
COMMENTS
Exponential Riordan array [exp(-x^2), 2x]. - Paul Barry, Jan 22 2009
REFERENCES
Jerome Spanier and Keith B. Oldham, "Atlas of Functions", Hemisphere Publishing Corp., 1987, chapter 24, equations 24:4:1 - 24:4:8 at page 219.
LINKS
T. D. Noe, Rows n=0..100 of triangle, flattened
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972, p. 801.
Taekyun Kim and Dae San Kim, A note on Hermite polynomials, arXiv:1602.04096 [math.NT], 2016.
Alexander Minakov, Question about integral of product of four Hermite polynomials integrated with squared weight, arXiv:1911.03942 [math.CO], 2019.
Wikipedia, Hermite polynomials.
FORMULA
T(n, k) = ((-1)^((n-k)/2))*(2^k)*n!/(k!*((n-k)/2)!) if n-k is even and >= 0, else 0.
E.g.f.: exp(-y^2 + 2*y*x).
From Paul Barry, Aug 28 2005: (Start)
T(n, k) = n!/(k!*2^((n-k)/2)((n-k)/2)!)2^((n+k)/2)cos(Pi*(n-k)/2)(1 + (-1)^(n+k))/2;
T(n, k) = A001498((n+k)/2, (n-k)/2)*cos(Pi*(n-k)/2)2^((n+k)/2)(1 + (-1)^(n+k))/2.
(End)
Recurrence for fixed n: T(n, k) = -(k+2)*(k+1)/(2*(n-k)) * T(n, k+2), starting with T(n, n) = 2^n. - Ralf Stephan, Mar 26 2016
The m-th row consecutive nonzero entries in increasing order are (-1)^(c/2)*(c+b)!/(c/2)!b!*2^b with c = m, m-2, ..., 0 and b = m-c if m is even and with c = m-1, m-3, ..., 0 with b = m-c if m is odd. For the 10th row starting at a(55) the 6 consecutive nonzero entries in order are -30240,302400,-403200,161280,-23040,1024 given by c = 10,8,6,4,2,0 and b = 0,2,4,6,8,10. - Richard Turk, Aug 20 2017
EXAMPLE
[1], [0, 2], [ -2, 0, 4], [0, -12, 0, 8], [12, 0, -48, 0, 16], [0, 120, 0, -160, 0, 32], ... .
Thus H_0(x) = 1, H_1(x) = 2*x, H_2(x) = -2 + 4*x^2, H_3(x) = -12*x + 8*x^3, H_4(x) = 12 - 48*x^2 + 16*x^4, ...
Triangle starts:
1;
0, 2;
-2, 0, 4;
0, -12, 0, 8;
12, 0, -48, 0, 16;
0, 120, 0, -160, 0, 32;
-120, 0, 720, 0, -480, 0, 64;
0, -1680, 0, 3360, 0, -1344, 0, 128;
1680, 0, -13440, 0, 13440, 0, -3584, 0, 256;
0, 30240, 0, -80640, 0, 48384, 0, -9216, 0, 512;
-30240, 0, 302400, 0, -403200, 0, 161280, 0, -23040, 0, 1024;
MAPLE
with(orthopoly):for n from 0 to 10 do H(n, x):od;
T := proc(n, m) if n-m >= 0 and n-m mod 2 = 0 then ((-1)^((n-m)/2))*(2^m)*n!/(m!*((n-m)/2)!) else 0 fi; end;
# Alternative:
T := proc(n, k) option remember; if k > n then 0 elif n = k then 2^n else
(T(n, k+2)*(k+2)*(k+1))/(2*(k-n)) fi end:
seq(print(seq(T(n, k), k = 0..n)), n = 0..10); # Peter Luschny, Jan 08 2023
MATHEMATICA
Flatten[ Table[ CoefficientList[ HermiteH[n, x], x], {n, 0, 10}]] (* Jean-François Alcover, Jan 18 2012 *)
PROG
(PARI) for(n=0, 9, v=Vec(polhermite(n)); forstep(i=n+1, 1, -1, print1(v[i]", "))) \\ Charles R Greathouse IV, Jun 20 2012
(Python)
from sympy import hermite, Poly, symbols
x = symbols('x')
def a(n): return Poly(hermite(n, x), x).all_coeffs()[::-1]
for n in range(21): print(a(n)) # Indranil Ghosh, May 26 2017
(Python)
def Trow(n: int) -> list[int]:
row: list[int] = [0] * (n + 1); row[n] = 2**n
for k in range(n - 2, -1, -2):
row[k] = -(row[k + 2] * (k + 2) * (k + 1)) // (2 * (n - k))
return row # Peter Luschny, Jan 08 2023
CROSSREFS
KEYWORD
AUTHOR
Vladeta Jovovic, Apr 30 2001
STATUS
approved